/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace Spring.Data.Core;

/// <summary>
/// Adapter implementation of the ResultSetExtractor interface that delegates
/// to a RowMapper which is supposed to create an object for each row.
/// Each object is added to the results List of this ResultSetExtractor.
/// </summary>
/// <remarks>
/// Useful for the typical case of one object per row in the database table.
/// The number of entries in the results list will match the number of rows.
/// <p>
/// Note that a RowMapper object is typically stateless and thus reusable;
/// just the RowMapperResultSetExtractor adapter is stateful.
/// </p>
/// <p>
/// As an alternative consider subclassing MappingAdoQuery from the
/// Spring.Data.Objects namespace:  Instead of working with separate
/// AdoTemplate and IRowMapper objects you can have executable
/// query objects (containing row-mapping logic) there.
/// </p>
/// </remarks>
/// <author>Mark Pollack (.NET)</author>
public class RowMapperResultSetExtractor : IResultSetExtractor
{
    private readonly IRowMapper rowMapper;
    private readonly RowMapperDelegate rowMapperDelegate;
    private readonly int rowsExpected;

    /// <summary>
    /// Initializes a new instance of the <see cref="RowMapperResultSetExtractor"/> class.
    /// </summary>
    public RowMapperResultSetExtractor(IRowMapper rowMapper) : this(rowMapper, 0, null)
    {
    }

    public RowMapperResultSetExtractor(IRowMapper rowMapper, int rowsExpected) : this(rowMapper, rowsExpected, null)
    {
    }

    public RowMapperResultSetExtractor(IRowMapper rowMapper, int rowsExpected, IDataReaderWrapper dataReaderWrapper)
    {
        //TODO use datareaderwrapper
        this.rowMapper = rowMapper ?? throw new ArgumentNullException(nameof(rowMapper));
        this.rowsExpected = rowsExpected;
    }

    public RowMapperResultSetExtractor(RowMapperDelegate rowMapperDelegate)
        : this(rowMapperDelegate, 0, null)
    {
    }

    public RowMapperResultSetExtractor(RowMapperDelegate rowMapperDelegate, int rowsExpected)
        : this(rowMapperDelegate, rowsExpected, null)
    {
    }

    public RowMapperResultSetExtractor(RowMapperDelegate rowMapperDelegate, int rowsExpected, IDataReaderWrapper dataReaderWrapper)
    {
        //TODO use datareaderwrapper
        this.rowMapperDelegate = rowMapperDelegate ?? throw new ArgumentNullException(nameof(rowMapperDelegate));
        this.rowsExpected = rowsExpected;
    }

    public object ExtractData(System.Data.IDataReader reader)
    {
        // Use the more efficient collection if we know how many rows to expect:
        // ArrayList in case of a known row count, LinkedList if unknown
        var results = new List<object>(rowsExpected);
        int rowNum = 0;
        if (rowMapper != null)
        {
            while (reader.Read())
            {
                results.Add(rowMapper.MapRow(reader, rowNum++));
            }
        }
        else
        {
            while (reader.Read())
            {
                results.Add(rowMapperDelegate(reader, rowNum++));
            }
        }

        return results;
    }
}
